realize chronostratigraphic correlations. Apart from the race to the oldest hominin site, defining the chronological relations among hominid species and artifacts is an exciting field of research. References and Notes

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Brewer, T.E., Albertsen, M., Edwards, A., Kirkegaard, R.H., Rocha, E.P.C., Fierer, N., 2020. Unlinked rRNA genes are widespread among bacteria and archaea. The ISME Journal 14, 597-608.

https://doi.org/10.1038/s41396-019-0552-3 Ribosomes are essential to cellular life and the genes for their RNA components are the most conserved and transcribed genes in bacteria and archaea. Ribosomal RNA genes are typically organized into a single operon, an arrangement thought to facilitate gene regulation. In reality, some bacteria and archaea do not share this canonical rRNA arrangement - their 16S and 23S rRNA genes are separated across the genome and referred to as 'unlinked'. This rearrangement has previously been treated as an anomaly or a b yproduct of genome degradation in intracellular bacteria. Here, we leverage complete genome and long-read metagenomic data to show that unlinked 16S and 23S rRNA genes are more common than previously thought. Unlinked rRNA genes occur in many phyla, most significantly within Deinococcus-Thermus, Chloroflexi, and Planctomycetes, and occur in differential frequencies across natural environments. We found that up to 41% of rRNA genes in soil were unlinked, in contrast to the human gut, where all sequenced rRNA genes were linked. The frequency of unlinked rRNA genes may reflect meaningful life history traits, as they tend to be associated with a mix of slow-growing free-living species and intracellular species. We speculate that unlinked rRNA genes may confer selective advantages in some environments, though the specific nature of these advantages remains undetermined and worthy of further investigation. More generally, the prevalence of unlinked rRNA genes in poorly-studied taxa serves as a reminder that paradigms derived from model organisms do not necessarily extend to the broader diversity of bacteria and archaea.

Broeckhoven, K., Desmet, G., 2020. Advances and challenges in extremely high-pressure liquid chromatography in current and future analytical scale column formats. Analytical Chemistry 92, 554-560.

https://doi.org/10.1021/acs.analchem.9b04278 The present study speculates on the potential gain we can expect of a further leap in pressure by moving from the current 1500 bar to a futuristic 3000 bar as well as reviews the main impediments to be expected when trying to realize such systems. The study focuses on so- called 'analytical scale' separations, i.e., separations that are currently carried out in 2.1 mmcolumns, as this is the current state-of-the-art in ultrahigh-pressure liquid chromatography (UHPLC) instrumentation.

Brüske, A., Weyer, S., Zhao, M.Y., Planavsky, N.J., Wegwerth, A., Neubert, N., Dellwig, O., Lau, K.V., Lyons, T.W., 2020. Correlated molybdenum and uranium isotope signatures in modern anoxic sediments: Implications for their use as paleo-redox proxy. Geochimica et Cosmochimica Acta 270, 449-474.

http://www.sciencedirect.com/science/article/pii/S0016703719307392